JPS6231282B2 - - Google Patents

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to an optical measuring device for measuring physical quantities such as position, velocity, acceleration, force, pressure, elongation, and temperature, which comprises at least one optical fiber. transmits light between the electronic unit E and the transducer G, and an optical modulator provided in this transducer is actuated directly or indirectly by the measurand quantity in question. The present invention relates to an optical measuring device which is adapted to modulate the light emitted to the transducer depending on the transducer.

BACKGROUND OF THE INVENTION A major problem with fiber-optic analog converters is that it is quite difficult to obtain stability between the fiber and the opto-component.

SUMMARY OF THE INVENTION It is an object of the invention to provide a solution to these and other related problems in measuring devices of the type mentioned above. The measuring device according to the invention is characterized in that the transducer is equipped with at least one optical filter having at least one of spectrally variable absorption, transmission and reflection effects within the spectrum of the light used; A filter transmits at least one stabilizing signal within one wavelength range and at a different wavelength in order to compensate for changes in fiber optics in the light emitted from the converter. each is adapted to generate at least one measurement signal within the region;
The stabilization signal is characterized in that it is less dependent on the physical quantity to be measured than the measurement signal. This type of measuring device is stable and has general application to fiber optical transducers.

In this way stable measurements and a high degree of precision of the measurements can be obtained.

In another preferred embodiment, the fiber conducts light from at least one light source in the electronic unit to a converter and also conducts light from the converter to one or more photodetectors in the electronic unit. The transducer includes at least one optical interference filter, which is influenced directly or indirectly by the physical quantity to be measured, and which is influenced by the physical quantity to be measured so that the transducer has at least one optical interference filter. Modulate light. The present invention is characterized in that the physical quantity influences the optical wavelength of light in an interference layer constituting the interference filter. This results in a movement of the transmission and reflection spectra, which, based on a suitable selection of the wavelength of the measuring light, can be split into both measuring and stabilizing components in the electronic unit E. This will generate a signal.

EXAMPLES The invention is illustrated in more detail in the accompanying drawings, in which: FIG.

FIG. 1 shows a measuring device according to the invention, which is equipped with two light sources 1 and 2.
emits light with different distributions of wavelengths (maximum at wavelengths λ ₁ and λ ₂ , respectively) into photoconducting fibers 3 and 4, respectively, and the lights from the two branches are merged into one at fiber 5. It's summery. The electronic unit is defined by the dashed rectangle E and the transducer by the square G. A portion of the light from fiber 5 is passed through fiber 6 to a photodetector 18 in electronic unit E;
Further, the photocurrent of this photodetector is amplified by 19 and supplied to a difference generator 20 together with a reference voltage 21 (V _ref ), and this difference is further used as a regulator 2.
An error signal to the light emitting diode 1 is configured and transmitted to the light emitting diode 1 through the drive circuit 24 depending on the position of the switch 23.
Alternatively, the light emitting diode 2 is adjusted through the drive circuit 25. This adjustment ensures that the relationship between the light intensities from the light emitting diodes 1 and 2 remains constant. Switch 23 is adjusted by oscillator 17 between two positions. fiber 5
The light from the light emitting diodes 1 and 2 is passed through the fiber 7. The fiber 7 conducts the light to a converter G, which in this figure is provided with an optical filter 9 in the gap 8 between the fiber 7 introducing the light and the fiber 10 conducting the light out. The fiber 10 also converts the light into a converter G.
The signal is then passed through a photodetector 11 in the electronic unit. The output signal of the photodetector 11 is amplified by the amplifier 12, and the output signal is further amplified by the switch 26 to the sample and hold circuit 13 at the same rate as the switch 23 switches the light emitting diodes 1 and 2, respectively.
and 14 alternately. The switch 26 is
Like switch 23, it is regulated by oscillator 17. The output of the circuit 13 thus inputs the value of the intensity of the light from the light emitting diode 1 after passing through the photoconductors 3, 5, 7, 10 and the converter G, and the output of the circuit 14 inputs the value of the intensity of the light from the light emitting diode 1 after passing through the photoconductor The value of the intensity of the light from the light emitting diode 2 after passing through the bodies 4, 5, 7, 10 and the converter G is input. The position of the optical filter 9 in the transducer determines the measurement quantity in question (position, velocity, acceleration, force, pressure, extension,
temperature, etc.), and the filter 9
By selecting
, and after the formation of the quotient in the divider circuit 15 a signal is obtained which, depending on the measured quantity, is influenced by the fiber optics and optoelectronics in the measuring device. is unrelated to parameter changes. The output signal from the divider circuit 15 is fed to a recording or indicating device 16, thus indicating the measured quantity.

One condition in the above method to provide complete compensation for microbending changes in the fiber optic is that the same mode of light is obtained from both light emitting diodes 1 and 2. This is because otherwise the microbending would affect the light from the two light emitting diodes differently, so that the quotient by 15 would not be constant.
In order to make the modes identical, light emitting diodes with the same spatial distribution of radiation are selected and mode mixing is carried out as far as possible by suitable bending of the fibers 3 and 4. mode·
Mixing refers to changing the mode distribution within the light guide by mixing different modes. If we use a light emitting diode with a conveniently defined light distribution,
These can be mounted next to each other in front of the ends of the fibers 5, as is clear from FIG. 1a. This makes it difficult to branch out fiber optics. Similarly, the photodiode 18 can also be placed in the vicinity of the light-emitting diodes 1 and 2, thus eliminating the need for the fiber 6. The end of the fiber 5 is preferably conical in front of the light emitting diode to receive more light. In order to ensure that the wavelength distribution of the light emitting diode is constant, a temperature regulator may be used to stabilize the temperature of the light emitting diode.

FIG. 1b illustrates a temperature regulator that can be adjusted either by the temperature of the light source or by the spectral distribution of the light from the light source. The latter method of adjustment is illustrated in FIG. 1b, in which a portion of the light from the light source 1 is passed through a filter 81 by the fiber 5 and the portion between fibers 5 and 7 to the photodetector. It has been sent to 82. The filter 81 is selected such that its transmission curve has an upward slope or a downward slope, and this slope intersects the curve of the light spectrum of the light source 1, so that changes in the spectrum of the light source 1 are reflected in the light of the detector 82. This results in a change in current. The desired temperature stabilization is obtained by a feedback circuit through an amplifier 83, a difference former 84 and a regulator 85, and a drive circuit 86 to a Peltier element 87. Figure 1b further shows how one light source can be used to generate the various wavelength ranges required for this device. When the switch 23 is in the lower position, 1
The light from 1 is adjusted to a value corresponding to V _1ref so that 1 acts as a light emitting diode and emits a wide spectrum of light, and in this way the light is reflected and transmitted in the light modulating filter 9. However, it is assumed that this filter 9 is of an interference type (see FIG. 1). When this switch is in the upper position, the light is adjusted to a value corresponding to (V _1ref +V _2ref ), whereby 1 behaves as a laser diode and, depending on the filter selection, is reflected at the filter 9. emit a narrow spectrum that can be transmitted or transmitted.

This means that when the switch 23 is in the lower position,
Since the current of the light source 1 is below the threshold value, the light source works as a light emitting diode, and when the switch 23 is in the upper position, the current of the light source 1 is above the threshold value, so the light source works as a laser diode. It is from.

So-called tunable diode lasers can also be used to generate different spectra at different times. By modulating the wavelength of the diode laser through the spectral transmission end of filter 9 (see Figure 1), an optical signal is obtained which is somewhat dependent on the movement of this filter, and this optical signal is as described above. It can be used to stabilize the measuring device.

FIG. 1 shows that the stabilization of optoelectronics and fiber optics can be achieved by time multiplexing of two light emitting diodes and by forming a quotient between the light components emitted by the two light emitting diodes and passed through a transducer. This figure shows the configuration that can be used. In FIG. 2, stabilization is carried out by frequency multiplexing instead of time multiplexing and by amplification adjustment instead of quotient formation. The light from the light-emitting diodes 1 and 2 passes here through separate optical filters 27 and 28, respectively, and has a conveniently separated spectral distribution (wavelengths λ 1 and ₂ , respectively) before being integrated into fiber 5 through fibers 3 and 4. The maximum value is obtained at λ ₂ ). As in FIG. 1, a portion of the light from fiber 5 is transmitted through fiber 6 to photodetector 18, the output signal of which is amplified by 19. Light emitting diodes 1 and 2 are modulated to different frequencies ₁ and ₂ by oscillators 40 and 41, respectively, so that the output signal from 19 can be split into two components by bandpass filters 33 and 34. Here, the output signal from 33 is the one emitted from the light emitting diode 1, and the output signal from 34 is the one emitted from the light emitting diode 2.
After demodulation in circuits 35 and 36, the difference between the two components is obtained at 37 and fed to a regulator 38, which adjusts an adjustable amplifier 39 so that the output signal from 37 is held at zero. In this way a coincidence of light emitting diodes 1 and 2 is obtained. A portion of the light from fiber 5 is transmitted through fiber 7 to transducer 32, which in this case comprises a pressure transducer with a reflective, pressure-sensitive membrane 31. This thin film 31 and fiber 7
There is an optical filter between the end face of the
It reflects and transmits varying amounts of light from the two light emitting diodes 1 and 2. After being reflected by the filter 30 or after passing through the filter 30 and being reflected by the reflective thin film 31, a portion of the light that is reflected back to the fiber 7 is transmitted through the fiber 1.
0 and is sent to the photodetector 11. The output signal from 11 is amplified at 12 and then split by filters 45 and 46 into two components emitted by light emitting diodes 1 and 2, respectively. After demodulation at 47, the signal at modulation frequency ₁ is compared at 49 with a reference signal V _ref and the difference thus obtained is fed to a regulator 50, which regulates amplifiers 42 and 43 in series. Alternatively (see dashed line 44) regulator 50 may regulate amplifier 12 through switch 44. This adjustment compensates for changes in the fiber optic and optoelectronic parameters of the measuring device. A compensated measurement signal is obtained after demodulation of the output signal from filter 46 by converter 48 , and the measurement signal can further be read in indicator device 16 .

In FIG. 3, as in FIGS. 1 and 2,
A configuration is shown in which the light is split into two (possibly overlapping) wavelength regions on the detector side instead of on the light source side. Light from the light source 1 is conducted through fibers 3 and 7 to the transducer itself, which is equipped with a temperature-sensitive material, which is connected to an optical filter 30 and a mirror 3 at the fiber end.
It is placed in the beam path between 1 and 1. This material may be a semiconductor, for example, a bandgap,
Therefore, it is only necessary that the absorption of light changes depending on the temperature. The reflected light from filter 30 and mirror 31 is conducted back to fiber 7 so that a portion of the light passes through fibers 10, 56, and 57 to filters 53 and 54 and to photodetector 1.
1 and 51. Filter 53 is selected to pass more light than is directly reflected by filter 30, whereas filter 54 is selected to pass more light than is directly reflected by filter 30.
0 and is selected to pass more light than is acted upon by sensor 55 and reflected back into fiber 7 by mirror 31. After amplification in the amplifier 12 and comparison with the reference signal V _ref in the comparison device 49, the output signal from the detector 11 is used by the regulator 50 to adjust the light source 1 and thus Compensation for instability is obtained. The signal from the detector 51 constitutes the measurement signal, and because of the regulator 50 described above, reliance on optoelectronic and fiber optic instabilities, if any, is reduced. Here, a light emitting diode with a large half-value width is used as a light source.
However, as an alternative, two light emitting diodes with separate spectral distributions and corresponding to the optical filters 30, 53 and 54 may be used.

In the measuring device according to FIG.
A good match between and 51 is required. If this coincidence is not sufficient, electronic coincidence stabilization can be carried out according to FIG. FIG. 4 also illustrates another configuration of the photodiode. Through the drive circuit 24, the oscillator 40 modulates the light source 1, which emits light through the fibers 3 and 7 to the transducer, which is connected to the optical filter 30.
and the force cell 6 placed on the base 61
0 and a pressure sensitive modulator 59 with a reflective rear surface 31. Force F is modulator 5
9 and thus cause a varying absorption for the wavelength range used. The modulator may, for example, comprise a semiconductor with a pressure-dependent bandgap. Therefore, light that is not acted upon by the converter and is reflected by the filter 30 is acted upon by the converter and is transmitted by the filter 30 and the modulator 59 and is further reflected by the mirror 31. Similarly to the light that is transmitted, it will return from the transducer into fiber 7 and travel towards fiber 7 and fibers 10 and 58. At the end face of the fiber 58 there are two photodetectors 11 separated by a screen 71.
and 51. Light to photodetector 11 is passed through optical filter 53, but light at photodetector 51 is not passed through the filter. This means that
By appropriate selection of the light source 1, the filter 30 and the filter 53, it is meant that the measurand quantity is to influence the photodetectors 11 and 51 to varying degrees, and the filters at 62 and 65 respectively. After demodulation at 63 and 66, respectively, and quotient formation at 15, a measurement signal is obtained which is thus compensated for optoelectronic and fiber optic instabilities. In order to compensate for the coincidence between the photodetectors 11 and 51, the light source 2 passes the light modulated by the oscillator 41 through the fiber 4.
8 and photodetectors 11 and 51. The output signals from the light sensing amplifiers 12 and 52 are compared in a subtraction device 67 and the resulting signal is applied to the light source 2.
The output signal from 64 is filtered at 68 and demodulated at 69 before being provided to a regulator 70 which adjusts the adjustable amplifier 64 so that the output signal from 64 is filtered at 68 and demodulated at 69 before being provided to a regulator 70 which adjusts the output signal from 64 to the amplifier 12 for the signal component at frequency ₂ . so that it remains equal to the output signal from the This ensures matched detector channels 11-12 and 51-64.

Alternatives to the photodetector configuration of Figure 4 (indicated by the dashed rectangle) are shown in Figures 4a and 4.
The configuration shown in figure b can also be used. FIG. 4a also shows a fiber 58 and a photodetector 5.
1, and in FIG. 4b the photodetector 11 is connected to the filter 5.
The light transmitted by the photodetector 5 is detected by the photodetector 5.
1 is shown sensing light reflected by the same filter.

Figures 5a-51 briefly illustrate various sensor configurations that may be used in the transducer in question. In all cases except Figures 5f and 5j, the measured quantity is converted into a mechanical movement, which is detected by a filtered mirror or diffuser. In FIG. 5a, a filter 30 provides a predominant reflection within a particular wavelength range of the light being used, which is utilized to generate a reference signal that is largely independent of the measurand, and further In the wavelength range , there is a main transmission, which results in a measurement signal that is reflected by the mirror or diffuser 31 . An example of a possible selection of the light source and filter in the arrangement according to FIG. 5a is illustrated in FIGS. 6a to 6d, which corresponds to the measuring device according to FIG. 2. Figure 6a shows light source 1
and 2 are illustrated. The light source overlap for the filter 30 is shown in FIGS. 6c and 6d.
filters 27 and 28 according to the diagram, so that the light from the light source 1 is only slightly reflected by the filter 30 according to the reflection curve R in FIG. 6b (FIG. 2). , and the light from the light source 2 is only slightly transmitted by the filter 30 according to the transmission curve T in FIG. 6b. Naturally, the filters 27 and 28 are
and 4a can be placed on the photodetector side. All filters are suitably constructed as multilayer interference filters.

Instead of the measured quantity being provided by a vertical movement of the mirror/diffuser 31 according to the arrows in Figure 5a, the measured quantity can be converted into a lateral movement according to Figure 5b.
Mirror/diffuser 3 in Figures 5a and 5b
1 may be replaced by a filter 73 according to FIGS. 5c and 5d. In this way, from Figure 7a to Figure 7
Filter characteristics up to figure c can be used. The light (approximately λ ₁ ) from the light source 1 passes through the filter 30 (Fig. 7b) and then passes through the filter 73 (Fig. 7c).
The light (approximately λ ₂ ) from the light source 2 is reflected by the filter 30 (FIG. 7b) and then passes through the filter 73 (FIG. 7c). This improves the separation between the reference signal and the measurement signal from the transducer.

Yet another modulator configuration is illustrated in Figure 5e, in which filter 30 and mirror 31 are movable. Since the filter 30 reflects light of different wavelengths to varying degrees, both a measurement signal and a reference signal are obtained, although this is not the case with a mirror or diffuser 31. Focusing on the distance between the fiber end and the mirror/filter, this selects higher order modes and end rays from the fiber.

In addition to sensing mechanical motion, filter techniques can also be used to sense changes in the absorption of material 74 in Figure 5f. The resulting characteristic is the 8th
It is illustrated in Figures a through 8c. light source 2
(Fig. 8a) is passed through the filter 30 (Fig. 8b).
To some extent, the sensor material 7
4 (Fig. 8c). How much is transmitted by the sensor material depends on the measurand, which can be temperature, pressure, or the strength of a magnetic or electric field; follows the curve T ₁ in Fig. 8c,
For other values it will follow the curve T ₂ in FIG. 8c. The light from the light source 1 (FIG. 8a) is reflected by the filter 30 (FIG. 8b) and then absorbed by the sensor material, so that it is only slightly influenced by the measured quantity. Alternatively, mirror 31 may include a reflective filter to further separate wavelengths. By using a fixed filter 30 and several movable filters 73, 74, etc., information regarding several measured quantities can be transmitted over the same fiber 7. 5th g
In the figure, filters 73 and 74 both move up and down, and in Figure 5h, filter 73 moves in the x direction and filter 74 moves in the y direction. Possible filter characteristics are shown in Figures 9a to 9d.
Illustrated in the figures. Light source 1 (FIG. 9a) substantially provides reflection at filter 30 (FIG. 9b), while light source 2 is provided by filter 73 (FIG. 9c).
wavelength interval λ ₃ to _{λ 4} and the filter 74
(Figure 9d) gives the reflection in the wavelength interval λ ₄ -λ ₅ . By equipping the optical detector with filters in corresponding wavelength intervals, the individual operation of filters 73 and 74 can be obtained from the light reflected into fiber 7.

If an absorption filter is used, an arrangement with a movable filter 30 and a fixed mirror 31 according to FIG. 5i may be used. Furthermore, FIG. 5j shows an arrangement with an optical modulator 75, the reflection spectrum of which varies depending on the measured quantity in question.

The modulations are movable with respect to each other when greater resolution in the mechanical configuration is desired;
This is created by two screen patterns 76 and 77 (FIG. 5k) placed in front of the filter 30. The measured quantity moves the screen 77 with reflective particles relative to the screen 76 with absorbing particles. In addition to increased resolution, improved proportionality will be obtained as well as less influence of the mode distribution of the light. The latter can also be achieved using a diffuser or screen 77 at the fiber end with a coefficient matching medium 78. Filter 3
0 is placed behind 77 to ensure that both the reference light from 30 and the measurement light from mirror 31 pass through diffuser/filter 77.

FIG. 10 shows a measuring device with two light sources 101 and 102, which provide respective light-conducting fibers 103 and 104 with different wavelength distributions (maximum at λ ₁ and λ ₂ , respectively).
The fiber 105 emits light having a wavelength of 100 nm, and the light beams that are split at the fiber 105 become one. A portion of the light from fiber 105 passes through fiber 106 to photodetector 11.
8, this photocurrent is amplified by an amplifier 119 and then supplied to a difference former 120. A difference is thus formed between the reference voltage 121 (V _ref ) and the output signal from 119, which difference is
2, the regulator configures the error signal to the drive circuit 12
4 or adjust the light emitting diode 10 through the driving circuit 125.
2, which depends on the position of switch 123. With this adjustment method, switch 1
23 is adjusted by the oscillator 117 (see FIG. 10) between the two positions, it is ensured that the ratio between the light intensities from the light emitting diodes 101 and 102 remains constant. . Fiber 105 allows a portion of the light from light emitting diodes 101 and 102 to pass through fiber 107, which further conducts the light to a suitable converter. The transducer comprises two lenses 108 between which a rotatable interference filter 109 is placed. After passing through the filter 109, the fiber 1
The light transmitted through fiber 1
10 to a photodetector 111, the output signal of which is amplified in an amplifier 112 and then transmitted to a photodetector 111 as a switch 123 switches in light emitting diodes 101 and 102.
Sample and hold circuits 113 and 1 by 26
14 alternately. In this way, the output of 113 is
and the light emitting diode 101 after passing through the converter.
We will get the value of the light intensity from , and 11
The output of 4 is the photoconductor 104, 105, 107, 1
10 and the light emitting diode 1 after passing through the converter
The value of the light intensity from 02 will be obtained. The angular position of the interference of the filter 109 in the transducer is influenced by the measured quantity. By choosing the spectral transmission curve 165 of the interference filter 109 and the radiation curves 167 and 168 of the light sources 101 and 102 as illustrated in FIG. 11, the reduction of the angle α according to FIG. The curve is shifted to longer wavelengths as shown by the dashed curve 166, thereby decreasing the transmission of light from light source 101 and increasing the transmission of light from light source 102. This fact is used, on the one hand, to obtain a measurement signal indicating the rotation of the filter, and on the other hand, to obtain a reference signal for compensation of the instabilities of the light source, fiber optics and detector. The difference between the signals from sample and hold circuits 114 and 113 is estimated by using a difference former 127 (FIG. 10), which circuit comprises the values of the light signals emitted by light sources 102 and 101, respectively. ing. This difference is highly dependent on the measured quantity according to the angular position of the interference filter 109. On the other hand, the summing device 128 forms the sum of the light signals from the two light sources, and also adds the light transmission from one light source to the other.
Since the transmission of light from one light source increases when it decreases and vice versa, when the angular position of the interference filter changes, the output signal from 128 will be slightly dependent on the measurand and hence the reference It can be used as a signal. By forming a quotient at 115 between the difference and the sum, the measuring signal is input to the device 116, which is compensated for the instability in the measuring device already described.
Switches 123 and 126 and sample and hold circuits 113 and 114 transmit light signals from two light sources.
ie, instead of separation using time division multiplexing, frequency division multiplexing may be used. When frequency division multiplexing is used, switch 123 is replaced by two oscillators to modulate light sources 101 and 102 with different frequencies, while at the same time the sample and hold circuit is replaced by an electrically filtered demodulator to modulate light sources 101 and 102 with different frequencies. The signals from two light sources are separated and demodulated.

FIG. 12 shows a measuring device based on the same basic principle as in FIG. 10, but with a slightly different embodiment. As a light source, a broad spectrum light source according to the radiation spectrum 169 in FIG. 13 or a radiation spectrum 167 in FIG.
and 168, respectively. Light from the light source is conducted into fiber 103 and through fiber 107, which sends the light to the converter. In addition to the interference filter 130, the transducer connects the end face of the fiber 107 and the mirror 1
An air gap 108 is provided between the
Mirror 131 reflects a portion of the light back toward fiber 107 and fiber 110, from where the light is split into fibers 156 and 157, which reach filters 153 and 154, respectively. These transmission curves are illustrated in FIG.
3 and curve 171 corresponds to filter 154. As the interference angle α decreases, the transmission curve of the interference filter moves toward longer wavelengths, as illustrated by transmission curve 166. This means that even less light is transmitted by filter 153 (curve 170) and more light is transmitted by filter 154 (curve 171), provided that the light source has a sufficient spectrum. Assume that it has a width. Thus, the reference signal is transmitted to detector amplifier 112 which amplifies the detector signals from detectors 111 and 151, respectively.
and 152 directly. This reference signal is formed in a summing device 128, the output signal of which is compared in a difference former 120 with a reference signal V _ref (from 121). The difference former 120 is connected to a regulator 122 which is connected to the light source 10 by a drive circuit 124.
1 to keep the output signal from 128 equal to _Vref . The measurement signal is sent to the difference former 127
and is provided to a recording or indicating device 116.

The measuring device described in FIGS. 10 and 12 can be used to measure most physical quantities that can be converted into mechanical angular motion. The light modulation interference filter is therefore mounted in such a way that a reproducible rotational motion can be obtained. This is done, for example, by center point bearings, torsional suspension, bending suspension or buckle suspension. However, shifting the spectral transmission curve of the interference filter described in FIGS. 11 and 13 is done in a different way than rotating the filter. Thus, if the optical wavelength in the interference layer constituting the interference filter is varied by the filter in the direction in which it is moved, then the movement of the filter 172 is as described above (see the double-headed arrow). (see) How light modulation can be provided is illustrated in Figure 14a. It is also possible to influence the optical wavelength by introducing mechanical stress into the interference layer. The stress is applied directly to the body 174 according to FIG. 14b, and the body is subjected to the force F to be measured. The interference filter will then operate as an elongation transducer. Furthermore, the filter 173 in FIG. 14c is capable of sensing ambient pressure and ambient temperature by the dependence of the optical wavelength on these physical quantities.

Finally, FIG. 15 illustrates how the reflection spectrum of an interference filter can be used to obtain the same type of light modulation as described in FIGS. 10 and 12. Fiber 107 (first
0) is reflected by filter 109 towards fiber 110, whereby the spectral distribution of the reflected light can be shifted by changing the angle α.

However, using the reflection spectrum involves the difficulty that in addition to the aforementioned spectral modulation, a modulation of the coupling between fibers 107 and 110 is also obtained. To overcome this to some extent, the fibers 107 have a small diameter to conduct the light inward and the fibers 11 have a large diameter and a large number of apertures to conduct the light out.
The use of 0 is illustrated in FIG. Alternatively, fiber 107 can be replaced with a larger diameter fiber if fiber 110 is replaced with a cube-cornered reflector. This allows fiber 107 to conduct light both outward and inward.

The device described above can be varied in many ways within the scope of the claims.

[Brief explanation of the drawing]

FIG. 1 shows a measuring device with two light sources. FIG. 1a shows the fiber end on the electronic unit side, and FIG. 1b shows the temperature stabilization measuring device. FIG. 2 is a diagram showing a measuring device using frequency division multiplex transmission stabilization. FIG. 3 shows a measuring device that divides light into two wavelength regions of a filter in a photodetector. Fourth
The figure shows a measuring device with electronic coincidence stabilization of the light source. Figures 4a and 4b illustrate two different filter configurations in a photodetector. Figures 5a to 5l are diagrams showing various examples of sensor configurations. Figures 6a to 6d, Figures 7a to 7c, Figures 8a, 8c, and 9
Figures a through 9d show curves for various spectral distributions when various filters and optical modulators are used. FIG. 10 shows another measuring device with two light sources and a rotatable interference filter. FIG. 11 is a diagram showing the radiation curve of the light source and the transmission curve of the filter in the measuring device of FIG. 10. FIG. 12 is a diagram showing another embodiment of FIG. 10, and FIG. 13 is a diagram showing another embodiment of FIG.
FIG. 3 is a diagram showing a radiation curve of a light source and a transmission curve of a filter in the measuring device of FIG. 2; Figure 14a~
FIG. 14c shows various filter arrangements in the measuring device of FIG. 11 or 12. FIG. 15 is a diagram showing a fiber configuration when the reflection spectra in FIGS. 10 and 12 are used. Explanation of reference symbols, E...electronic unit, G...converter, 1, 2...light source, 5, 7...optical fiber, 9...optical filter, 11, 18...photodetector, 12...amplifier, 15...component Formator, 27,
28... Optical filter, 30... Optical modulator, 31... Mirror, 39... Adjustable amplifier, 42, 43... Series connected amplifier, 45, 46...
Filter, 73... Filter, 109... Rotatable interference filter, 131... Mirror.

Claims (1)

Claims: 1. A position comprising electronic circuit means E, a transducer G and at least one optical fiber;
An optical measuring device for measuring physical quantities such as velocity, acceleration, force, pressure, elongation, temperature, etc., wherein the electronic circuit means has at least one light source that emits light and means for processing a measurement signal. , the converter that receives the emitted light is equipped with a light modulation means that is acted upon directly or indirectly by the physical quantity to be measured, whereby the received light is modulated. the optical fiber is adapted to conduct light between the at least one light source and the converter, and the light modulating means is adapted to conduct light emitted by the at least one light source. Within the spectrum of
Absorption characteristics, transmission characteristics, whose spectra change,
and at least one optical filter 9 having reflective properties or any of the above,
The filter provides at least one stabilizing signal in one wavelength range and in another different wavelength range to compensate for changes in fiber optics in the light output from the converter. Inside,
Optical measuring device, characterized in that it is adapted to generate at least one measuring signal, the stabilizing signal being less dependent on the physical quantity to be measured than the measuring signal. 2. The optical measuring device according to claim 1, wherein the filter 9 includes an interference filter. 3. According to claim 2, the filter is actuated directly or indirectly by the physical quantity to be measured, and modulates the light in the converter based on the effect of the physical quantity, An optical measuring device characterized in that the physical quantity acts on an optical distance of light in an interference layer constituting the interference filter. 4. The optical measuring device according to claim 2, wherein at least one fiber end of the converter is provided with the interference filter 73. 5. According to claim 1, the transducer has at least one fiber end 7, and the light modulation means include at least one mirror 31, at least one screen, placed in the beam path in the transducer. pattern, and at least one
one or more diffusers;
The change in the physical quantity is adapted to cause a relative movement between the fiber end, the mirror, the screen, the diffuser, and/or any of them. Optical measurement equipment. 6. In claim 1, the light modulation means includes a light modulator placed in the path of the beam in the converter, and the change in the physical quantity is caused by reflection action, absorption, etc. of the light modulator 30. An optical measuring device characterized in that it is adapted to produce a change in action and/or transmission action. 7. In any one of claims 1 to 6, the at least one light source includes at least one light emitting diode, a laser diode, and/or other light source means, and the filter the transmission, absorption and/or reflection properties of the transducer are different in different parts of the light spectrum, and the light emitted from the transducer is directed to at least one light emitting diode 11, 18. An optical measuring device characterized by: 8. In claim 1, the at least one light source and/or a photodetector included in the electronic circuit means is provided with optical filters 27 and 28. An optical measuring device featuring: 9. Claim 7 provides that there are at least two light sources, that the at least two light sources are time-division multiplexed or frequency-division multiplexed, and that the electronic circuit means 1. An optical measurement device comprising a detection circuit equipped with an electronic device for demultiplexing light sources emitted from a device. 10. According to claim 7, the light intensity of the light source is adjusted by a separate light return to at least one detector 18 adjusting at least one regulator 39, 43 connected to the light source. An optical measuring device characterized in that it is maintained constant by 11. In claim 3, the optical distance is changed by rotating the interference filter 109, or the optical distance is different in different parts of the interference filter, and the filter is movable perpendicular to the beam path in the transducer, or the optical wavelength is varied by mechanical stress in the interference layer, or the optical wavelength is dependent on the temperature of the interference filter. An optical measuring device characterized by being designed to change as it twists. 12. The optical device according to claim 3, wherein the electronic circuit means includes a device for measuring transmission or reflection characteristics of the interference filter in the at least two unequal wavelength regions. measuring device. 13. In claim 12, the wavelength range corresponds at least in part to a spectral transmission peak or reflection peak of the interference filter, and the wavelength range is located on either side of the maximum value of the peak. An optical measuring device characterized by: 14. The optical measuring device according to claim 12, characterized in that the difference between the values of the transmission or reflection characteristics is used as a measurement signal, and the sum of the values is used as a stabilization signal. . 15. The optical measuring device according to claim 9 or 14, wherein the signal input to the detection circuit is supplied to a quotient generator 15. 16 In claim 9 or 14, one of the signals input to the detection circuit is:
the at least one light source and a detector amplifier;
or an optical measuring device that is supplied to a regulator that adjusts any of the above. 17 In claim 1 or 7, the electronic circuit means includes means for matching at least two of the photodetectors, and the matching means matches the light of a specific modulation frequency ₂ to the photodetector. an adjustable amplifier after one of said detectors by means of a regulator, further after demodulation, by supplying a constant rate to a detector and forming a difference signal of said detector signals with respect to this modulation frequency; 42 and 12 so that the difference becomes zero. 18. The optical measuring device according to claim 1 or 7, wherein the light source is temperature stabilized.